Seasonal nature of pineal secretion will be studied by pinealectomy, hormone measurement and beta-adrenergic challenge test. Seasonal nature of gonadotropin secreting capability of pituitary will be studied by hormone measurement and gonadotropin releasing hormone challenge test. Feedback relationships between ovarian follicles and pituitary gonadotropin secretion will be studied and follicle steroidogenesis capabilities will be examined. The existence of a photo-sensitive time for stimulating sexual recrudescence and the potential involvement of pineal hormones (melatonin) in the sensitization during this time will be studied. Possible binding of malatonin by hypothalamic tissues will be evaluated.